(a) Field
This disclosure relates generally to a method of controlling an electromechanical brake device, and more particularly to a method of controlling a system using a brake device that can perform an electronic parking function and having an electromechanical parking function that can perform a primary braking function with an electronic and complex mechanical method.
(b) Description of the Related Art
In general, a parking brake uniformly distributes a force that is applied to a parking cable by pulling a parking brake lever connected to a brake mechanism mounted in a wheel through an equalizer, and thus the brake mechanism restricts the wheel to thereby prevent a vehicle from moving.
In this way, when braking a wheel by manipulating a parking brake lever, a driver should manually operate a parking brake lever for braking while parked. However, it is inconvenient to perform a manual operation at this time, and the driver often forgets to carry out the manual operation. There accordingly is danger of a safety accident.
In order to address the inconvenience of such a manual method, an Electrical Parking Brake (EPB) is implemented that enables a braking state to be safely maintained by a driver when simply performing a parking operation upon parking by using the driving torque of a motor.
A braking system that can perform complex active control by using a hydraulic pressure and an electromechanical element are of electro-hydraulic brake (EHB, the same term as hEMB) and electric motion booster types.
Here, a braking system using a brake device having a complex electromechanical parking function using hydraulic pressure and an electromechanical element performs a parking function using an electromechanical element of a front wheel, and when a parking function is released, by appropriately distributing a braking force of a front wheel and a rear wheel by hydraulic pressure and an electromechanical element step by step, primary braking may be executed.
However, in a braking system using a brake device having a conventional electromechanical parking function, when the vehicle releases an EPB when parked on a sloping road and descends when a primary braking pedal is not released, if a gap between a primary piston and a secondary piston is not secured, additional braking force may not occur.
That is, when a gap between the primary and secondary pistons is not secured, booster power operating when the primary piston presses the secondary piston cannot be used due to an area difference between the primary piston and the secondary piston. Thus, a problem occurs in that an additional current should be applied to an electric motion motor corresponding to an electromechanical element when a braking force is applied, or the braking force that a driver requires may not be produced.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.